In the prior art, there have been known a liquid state detecting element and a liquid state detecting sensor, which are provided with a pair of detecting electrodes for detecting the state of a liquid on the basis of a variation of an electrostatic capacity between the electrodes.
The liquid state detecting element is exemplified by either the liquid state detecting element, which is configured by forming a pair of detecting electrodes on a printed circuit board, or the liquid state detecting element which is configured by fusing a pair of detecting electrodes with an insulating film (as referred to JP-A-63-079016 (a printed circuit board 1 and a detecting circuit 5) and JP-A-4-258725 (an electrostatic type level sensor)).
Here, the liquid state detecting element configured by using the printed circuit board has a large thickness size for the printed circuit board so that it is not proper for the application demanding a size reduction (or a thickness reduction). However, the liquid state detecting element configured by using the insulating film has a small thickness size so that it can be arranged in a small space and can satisfy the demand for the size reduction (or the thickness reduction).